This invention relates generally to the field of servers coupled to computer networks and more specifically to servers used as search engines.
Web servers are software applications hosted by computer systems operably connected to the Internet. Web servers receive requests from Web clients and provide responses in the form of documents written in a document markup language such as Hyper Text Markup Language (HTML). The first Web servers operated as connections to file systems and served static HTML documents stored as files within a computer system.
The static HTML documents were quickly replaced by programs that accept as input parameters a client request and generate as output a document. These programs are typically written in a variety of interpreted procedural languages such as Perl and acquired procedural languages such as C.
The use of document generating programs also introduced new capabilities. Data could be drawn from any source and used to create a document. For example, databases could be queried and the results used within a document. Furthermore, the document generating programs could create side effects during the execution of a document generating program. For example, a typical side effect may include creation and storage of tracking statistics for later use and analysis by a Web site's host.
The use of document generating programs created a bottleneck within a computer system hosting a Web server. Each document generating program ran in its own process and the constant creation and destruction of the required processes created unacceptable overhead requirements. These overhead requirements resulted in the creation of application servers capable of invoking document generation programs without creating new processes.
In one type of such an application server, the application server comprises an interpreter and the document generating programs are written in a proprietary programming language. In the case where the proprietary programming language is a procedural language, the application server reads and runs the document generating programs without invoking a new process. In the case where the proprietary programming language is an object oriented language such as Java, each document generating program is a software object known as a servlet. In this case, the Web server invokes the servlets as needed and the servlets handle the remaining document generation functions.
Previous development of Web servers focused on producing the most efficient use of computing resources to produce finer and finer vertical slices through a Web site. For example, a servlet once invoked includes all of the necessary logic necessary to acquire data according to a client request, format the acquired data into a document, and report back to the hosting system any statistics about the client/servlet interaction. Finer and finer vertical slices through a Web site leads to an unscalable Web server architecture because all the logic for acquiring data, generating a document, and producing side effects is included within a monolithic software object thus defeating the ability to reuse or integrate a particular software object in another system or software object.
Therefore, a need exists for a scalable Web server architecture that features a high degree of reusability of a Web server's components. The present invention meets such a need.